The invention relates to a one-piece bottle top with a deformable break-open seal.
The prior art has long embraced bottle tops molded in one piece, mostly in plastic material; such tops consist in a cap, generally a screw type, the bottom edge of which is connected by way of easily broken fillets with an annular seal that becomes separated at the moment when the bottle is first opened.
Tops of the type in question are fitted by being forced over and screwed onto the neck of the bottle, and are almost invariably provided with one or more inwardly-projecting elements located in such a way as to interfere with an annular bead offered by the bottle neck, thus bringing about the separation of the break-open seal when the cap is first twisted off to open the bottle.
Problems besetting manufacture of these bottle tops are connected essentially with the feasibility of their embodiment by molding, and in particular, with the difficulty of removing the formed article from the mold without damaging its break-open seal; similarly, the top must be fashioned in such a way as to enable easy fitment to the neck of the bottle, and to ensure that the cap part cannot be unscrewed unless the seal has first been broken.
One conventional top is provided with a break-open seal incorporating an inwardly-projecting element in the form of an annular rim. Such a rim is prevented from projecting too far, in view of the removal of the top from the mold and its subsequent forced fitment to the neck of the bottle; at the same time, the projection must ensure a degree of interference with the neck sufficient to produce an effortless separation of the seal when the cap is twisted off.
The defects commonly encountered with this design of top are traceable to variations in the dimensions of the bottle neck: if large, it becomes difficult to force the rim over the bead; if small, the cap will unscrew too easily, the seal fails to break open, and the entire top separates from the bottle. Other designs feature tongues or similar expedients, located internally of the seal, that flex when the top is fitted to the bottle initially, and function as interference elements when the cap is unscrewed; given the necessarily high degree of flexibility of such elements, this type of top also betrays the drawback that the cap can sometimes be twisted off without the seal breaking open.
The object of the invention is to overcome the drawbacks mentioned above, by providing a bottle top that is readily removable from the mold, easily fitted to the neck of a bottle utilizing automatic machinery, and which incorporates a break-open seal that is guaranteed to separate when the cap is first twisted off.
One advantage of the bottle top according to the invention is that, whilst evidently suitable for fitment to a bottle with a specially designed neck, it can also be used with bottles having a standard type neck profile such as those fashioned in plastic or glass commonly used for soft drinks, carbonated or otherwise.
A further advantage of the bottle top disclosed is that it will function correctly even though fitted to a bottle neck exhibiting dimensions that depart from a nominal specification, provided that such a departure falls within a given range of dimensional tolerances.